There actually was a backlash over seat belt laws back in the 80s when they were first being introduced. The backlash was nowhere near as widespread or furious, though, but it did exist, with tortured explanations trying to justify how they were a threat to civil liberties and/or that they hurt more people than they saved. Given how society has seen a substantially larger portion of the population descend into conspiratorial thinking, fueled by social media and partisan pundits (primarily on the right) and exacerbated by the previous administration and the current pandemic, if seat belt laws were introduced today and not 30-35 years ago it would elicit the same reactions were see towards mask and vaccine rules.

There is no joke.
https://www.history.com/news/seat-belt-laws-resistance